1. Field of the Invention
This invention relates to a rear suspension system adapted to be disposed on a bicycle having a rear wheel rotatable about a pivot point of a front triangle, and more particularly to a lightweight bicycle rear suspension system that is comprised of a small number of parts and that has a relatively high lateral stiffness.
2. Description of the Related Art
A conventional bicycle frame typically includes a front triangle, a rear triangle, and a shock-absorbing unit connected between the front and rear triangles. The front triangle includes a head or steering tube, a top tube, a down tube, a seat tube, and a bottom bracket mounted with a crank and pedal assembly. The rear triangle includes a seat stay and a chain stay.
FIG. 1 shows a first conventional rear suspension system 100 that is disposed on a bicycle frame, and that includes a shock absorber 101 and a single connecting rod 102 that are used to interconnect front and rear triangles 200, 300. While the first conventional rear suspension system 100 is simple in construction and lightweight, it is not sufficient in lateral stiffness, thereby affecting adversely the ride characteristics.
With further reference to FIG. 2, to promote the lateral stiffness, a second conventional rear suspension system 400 includes a shock absorber 401 and two connecting rods 402, 403. However, the lateral stiffness of the second conventional rear suspension system 400 is still insufficient due to lack of a connecting rod between a seat stay 301 and a chain stay 302 similar to the connecting rod 102 of the first conventional rear suspension system 100.
FIGS. 3, 4, and 5 show variations 500, 600, 700 of the conventional rear suspension systems 100, 400 of FIGS. 1 and 2, which have the same stiffness issues.
FIGS. 6, 7, and 8 show linkage systems 801, 802, 803, each of which can be added to the bicycle frame shown in FIG. 1 to increase stiffness. The linkage systems 801, 802, 803 have numerous disadvantages. For example, they are heavy, expensive to make, and complicated in construction.